package io.joyrpc.context;

/*-
 * #%L
 * joyrpc
 * %%
 * Copyright (C) 2019 joyrpc.io
 * %%
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 * #L%
 */

import io.joyrpc.extension.Extension;

import static io.joyrpc.Plugin.ENVIRONMENT;
import static io.joyrpc.context.ContextSupplier.CONTEXT_ORDER;

/**
 * 环境变量识别上下文
 */
@Extension(value = "environment", order = CONTEXT_ORDER)
public class EnvironmentContextSupplier implements ContextSupplier {

    protected Environment env;

    @Override
    public Object recognize(String key) {
        if (env == null) {
            env = ENVIRONMENT.get();
        }
        Property property = env.getProperty(key);
        return property == null ? null : property.getValue();
    }
}
